From Enterprise to Enterprise

From CV-6 to CVN-80, the developments of and improvements to aircraft-carrier design form a continuum from the early days of naval aviation to the horizon of tomorrow.

At the December decommissioning of the USS Enterprise (CVN-65), Secretary of the Navy Ray Mabus announced that the third carrier of the new Gerald R. Ford class, CVN-80, also will be called the Enterprise . It is the right time to reflect on how appropriate it is for CVN-80 to perpetuate that legendary name, for she is the product of the evolution of the two previous Enterprise s.

Tonnage Restrictions and Emerging Concepts

The first Enterprise carrier, CV-6, was designed under restrictions dictated by the 1921 Washington Naval Conference. Under the treaty terms, U.S. aircraft carriers were limited to an aggregate tonnage of 69,000; each new carrier could be no more than 27,000 tons. 1 How to divide the tonnage to get the most value? Was it five small carriers at 13,800 tons, or four at 17,250 tons, or three at 23,000 tons, or two at 27,000 tons? So from the beginning of naval aviation, the Navy debated whether more, smaller carriers are better than fewer, but larger carriers.

Indeed, the Navy initially designed one small carrier first at about 13,500 tons, the USS Ranger (CV-4), to see what it could get at the low end. The answer: not much. The Ranger was designed with too many compromises. She was slow, had poor sea-keeping, no underwater protection, and a small air wing. She could never fulfill her promise as an operational aircraft carrier because her small size precluded safe flight operations except in calm weather. 2

An exception to the Washington treaty allowed two carriers of 33,000 tons (with 3,000 more tons of growth margin) to be built on the hulls of unfinished battlecruisers, which became the USS Lexington (CV-2) and Saratoga (CV-3). 3 They were the first operational aircraft carriers, and their experiences in the fleet exercises of the 1920s greatly influenced the design of the Enterprise . In particular, the 1929 Fleet Exercise IX off the Panama Canal revealed the real capability of the aircraft carrier.

Built on their sleek battlecruiser hulls with a robust torpedo protection system, the Lex and Sara steamed at speeds above 30 knots. In each, four shafts were turned by four turbo-electric motors, powered by a massive electrical plant that generated more than 134 megawatts of electrical power. The Lex and Sara each were 850 feet at the waterline and had a large island complex to starboard consisting of two twin 5-inch/38-caliber gun mounts stacked in front of a conning/spotting tower. Aft of the tower an array of smokestacks served 16 boilers steaming below. The 888-foot flight deck had three centerline (scissors) aircraft elevators connecting it to the enclosed hangar bay. Each ship carried 90-plus aircraft.

The first vision of aircraft at sea supported Alfred Thayer Mahan’s concept of sea control. A carrier was expected to steam in line with the battleships to provide support by scouting ahead, offering protection, spotting the gunfire of the battleship line—but not attacking. 4 But in Fleet Exercise IX, the carriers were allowed to break away from the battleship line and operate independently. Detached from the main body, the Saratoga positioned herself about 150 miles off the coast and her air wing staged a dawn attack on the Panama Canal. Launching 83 aircraft in total, with 32 fighters providing overhead protection, 34 bombers made mock dive-bombing attacks on the canal’s Pedro Miguel and Miraflores locks.

Carriers Get Their Swarm On

It was a watershed event for naval aviation, and it established a winning approach: Steam more than 100 miles from the target, put as many aircraft as you can “deck-load” on the flight deck, then fuel and arm them. Launch them in a single, massive “swarming” strike that overwhelms the defensive systems of ships or land bases. The single “deck-load strike” launch formed the basis for U.S. carrier design that supported naval aviation’s swarming tactics. 6

But another crucial insight came in Fleet Exercise IX. After the attack on the Panama Canal, the carriers sent half the pilots and planes ashore at various times during the exercise to engage in mock air combat with the Army Air Corps flyers. The other half of the air wing remained on board and engaged in daylight flight operations to hone takeoff and landing skills.

With just half the planes on the flight deck during the day, the center-lined aircraft elevators were housed to the flight deck. This permitted continuous flight operations. What emerged was a realization that such operations could generate nearly as many sorties in a day with half the full complement than with all the aircraft crammed on board. 7 That insight from 1929 will still prove crucial for the Ford class.

With the benefits of the experiences of the Lexington and Saratoga in the fleet exercises of the 1920s, and with the Ranger’s poor sea-keeping and lack of speed because of her size, the USS Yorktown (CV-5) and Enterprise (CV-6) were designed longer and heavier than the Ranger , but still constrained in tonnage by treaty. 8 In 1931 the Navy considered 13 concept designs ranging from 13,800 tons to 27,000 tons. The final-design tonnage converged around 20,000 tons but retained many of the features of the larger Lexington ’s design: a starboard island complex of guns, conning tower, and stacks on a straight (axial) flight deck 800 feet long; the capability to deck-load 80-plus aircraft by three scissors aircraft elevators, and to launch them to execute the swarming strike. The hull on the Enterprise had Panamex dimensions with torpedo side protection. The power plant had nine boilers fueling four new, more efficient steam-turbine geared engines (rather than turbo-electric motors) turning four shafts to speeds of more than 32 knots, capable of launching the single “deck-load” swarming strike. 9

In 1939, The Yorktown/Enterprise design became the notional wartime design for the Essex class with improvements to ready-rooms, armor, and propulsion-plant arrangement that pushed displacement to 27,000 tons. Twenty-four ships were built as the backbone of the Fleet carrier force in World War II.

At sea during the 7 December 1941 attack on Pearl Harbor, the Enterprise ’s planes sank a Japanese submarine on 10 December. In 1942 the Enterprise played a key role in the Battle of Midway, stopping Japan’s advance there, and later at Guadalcanal. CV-6 would then go on the offensive and fight in nearly every battle in the Pacific war, earning 20 battle stars.

Postwar Problems, Design Solutions

The end of World War II brought the world into the nuclear age, and the next ship named Enterprise brought that new power to the carrier fleet. With the Cold War heating up, the aircraft carrier became one of the key platforms of the United States’ nuclear-deterrence strategy, which required large jet bombers. The Navy therefore designed a carrier capable of launching and recovering jet bombers as heavy as 100,000 pounds in all weather. Taking about 500 feet to land with an arresting wire around the clock, and 400 feet to catapult-launch at 175 knots while parking two squadrons of atomic bombers, the design required a flight deck to be about 1,100 feet long and 132 feet wide. With a speed requirement of 30-plus knots and a range requirement of 12,000 miles, the ship’s displacement was about 75,000 tons. 10

Those requirements drove the postwar design that became the carrier United States . Luckily, Secretary of Defense Louis Johnson canceled the United States in 1949 before the Navy would learn the terrible lesson of trying to recover heavier, faster jet aircraft on straight decks.

During the Korean War, Britain’s Royal Navy and the U.S. Navy were experiencing many accidents launching and landing the new heavier, faster jet aircraft on the straight-deck Essex -class carriers. The arresting system of wires and netting barriers that caught a lighter propeller-driven aircraft would not always stop the new-generation jets from crashing into the aircraft parked forward on the straight decks. 11

The British solution to this problem was threefold: steam catapults to launch the heavier jet aircraft; an angled deck to allow them to land with “power on” so they could bolter if they missed the arresting wires; and an optical landing aid that pilots could see, day or night, much farther out on the glide path than they could perceive a man on the flight deck with handheld paddles. 12

To be able carry out carrier-combat missions as in World War II plus fulfill the new all-important mission of nuclear deterrence, in all weather around the clock, the Forrestal class was super-sized to handle large jet bombers. The design incorporated an angled deck with four large deck-edge aircraft elevators, one to port at the front of the angled deck, and three to starboard. Also included were four steam catapults, an optical landing aid, and an island to starboard. To maximize reliability for the strategic nuclear-deterrence mission, the design arranged, inside a heavily torpedo-protected hull, four independent oil-fired propulsion plants powering four catapults, eight electrical generators and four turbine-geared engines; four shafts could achieve 30-plus knots to launch and recover more than 80 jet aircraft, including 24 atomic bombers.

With the Korean War raging, President Harry S. Truman’s administration proposed and Congress authorized six Forrestal -class carriers to be built at a rate of one per year from 1952 to 1957. In the meantime, the Navy fixed a design flaw in the port aircraft elevator, moving it aft and outboard of the angled landing area, and moving the island, putting two of three starboard aircraft elevators forward and one behind it.

A ‘Big E’ for the Nuclear Age

In 1958, Chief of Naval Operations Admiral Arleigh Burke released a three-year study titled “The Navy of the 1970 Era.” Six of 12 carriers would be nuclear-powered—as would 12 of 18 guided-missile cruisers and 18 of 54 guided-missile frigates. The overall plan called for six nuclear-powered task forces, each consisting of an attack carrier, two guided-missile cruisers, and three frigates. 13

That same year, China bombarded Quemoy and Matsu Islands in the Taiwan Strait. In response President Dwight D. Eisenhower’s administration proposed and Congress approved the building of a vessel that would be the nuclear version of the Forrestal class: the USS Enterprise (CVN-65).

Powered by four independent plants with eight nuclear reactors heating 32 steam generators that in turn ran 16 electrical generators, the Enterprise had four steam catapults and four turbine-geared engines turning four shafts to speeds of 30-plus knots. She could launch and recover more than 80 aircraft, including atomic bombers. What impressed operational commanders most was the extra steam and electrical power, and the space provided by the nuclear plant. The mighty carrier could steam at maximum speed with just six of her eight reactors for an extended period—months at a time—leaving all the on-board fuel available for the air wing. A Forrestal -class carrier, by contrast, would need all eight boilers online to make 30-plus knots and would have to refuel within five days—within 15 days if she used all the fuel on board, leaving none for aircraft.

In 1964, with her nuclear escorts USS Bainbridge (DLGN-25) and Long Beach (CGN-9), the Enterprise steamed around the world without refueling, traveling more than 31,000 miles in 65 days. That celebrated feat displayed a steaming capability that became more and more important as the threat of Soviet submarines grew as well as U.S. dependence on foreign oil.

With more than three times the ship-service electrical capacity of a Forrestal -class carrier, the Enterprise could host a variety of new electric-powered systems, such as the first electronically scanned fixed antennas—SCANFAR—which gave the Enterprise her unique rectangular island (she also carried a backup SPS-12 radar set). Also, because she did not have oil-fired boilers requiring 300,000 cubic feet of space for air intakes and smokestacks, all that volume could be used for other purposes. In particular, the ordnance and aviation-fuel capacity were increased by more than 30 percent on board the Enterprise over the Forrestal class.

However, all this flexibility and capability came at a premium—a 50-percent higher life-cycle cost over an oil-fired carrier. In the end, the Enterprise remained, literally, in a class all her own, while the Forrestal s continued being built. The Enterprise may have won the overall-capabilities contest, but the Forrestal s won the debate at the time over the cost of nuclear-powered vs. oil-fired. The USS America (CV-66) and John F. Kennedy (CV-67) increased the Forrestal class’s ranks.

‘A Two-Reactor Version of Enterprise ’

But the nuclear option would rise again. In 1964, with U.S. involvement in the Vietnam War expanding and aircraft carriers playing a greater role, the Navy conducted a new study of nuclear power with a focus on carriers. The study concluded that the additional advantage of nuclear power in reducing the vulnerability of logistic-support forces and operating without logistic forces in an emergency was worth the cost. 14

Two years later, Admiral Hyman G. Rickover finally convinced Secretary of Defense Robert S. McNamara of the virtues of a two-reactor-plant carrier; McNamara then proposed that the next three aircraft carriers should be nuclear-powered. Congress agreed, and the Nimitz class was born. 15

A Nimitz -class carrier is basically a two-reactor version of the Enterprise , with a significant reduction in life-cycle costs brought about by lowering the number of propulsion-plant components. Steam generators were reduced from 32 to 8 and electrical generators from 16 to 8, yet a Nimitz still could steam 4 turbines, turning 4 shafts at speeds of 30-plus knots to launch and recover more than 80 jet aircraft. However, even such noteworthy life-cycle savings would not quell the carrier critics until 1983, when Secretary of the Navy John Lehman convinced Congress of the value of two-ship buys that actually reduced the procurement costs of the follow-on Nimitz -class carriers that were acquired thusly. In all, ten Nimitz es were built.

In 1995, the Navy conducted a mission-area analysis and concluded it was time for a new carrier design, and the Department of Defense agreed. The DOD tasked the Navy to consider a clean-sheet design that not only maintained the core capability of carrier aviation, but improved flexibility and total life-cycle costs. This author was put in charge of the Navy’s program office that met that task.

The Navy defined the core capability of carrier aviation as the ability to operate forward, independently of air bases, where its aircraft must simultaneously perform surveillance, battlespace dominance, and strike-in-combat operations for extended periods. Concept designs looked at small carriers with 40 aircraft, medium carriers with 60, and large carriers with 80. Since their air wings could not handle strike and battlespace dominance simultaneously, the small carriers were set aside. Nuclear power was chosen as the preferred form of propulsion, and a new design was started while final ship size was determined.

13% More Cost, 100% More Performance

The DOD had the Navy study the performance of medium carriers with 55 aircraft vs. large carriers with 75 aircraft during a scenario in which a hostile regime closes the Persian Gulf and the carriers have to fight their way in and reopen it. The study showed that the large carriers launched roughly 8,000 sorties to the medium carriers’ 4,000 sorties. The large carriers cost 8 percent more than the medium carriers. Adding in the aircraft costs, the larger carriers cost 13 percent more. So for 13 percent more costs, large carriers get 100 percent more performance.

But what really convinced the DOD of the value of large carriers was testing that insight first learned in the Fleet Exercise of 1929. In the Persian Gulf scenario, the medium air wings were put on large carriers. Off large carriers the medium air wings flew 5,600 strike sorties, an improvement of 40 percent.

Why? U.S. carrier design puts 70 percent of the aircraft on the flight deck and houses 30 percent in the hangar. The larger flight deck allowed all 55 aircraft on it where they can be launched more quickly. With larger weapon magazines and fuel capacity, the large carriers stay online longer before refueling and rearming.

With less than a full complement of aircraft, a large carrier is more capable than the medium carrier fully loaded with that smaller complement. If the situation heats up, it is much quicker and cheaper to fill those empty spots on large carriers with aircraft than trying to make more spots by adding/building new carriers. Large carriers provide much more flexibility than smaller carriers.

To address the challenge of reducing total ownership costs, the Navy concluded that manning and ship procurements were the cost drivers. In terms of manning, the DOD required a reduction of 15 to 25 percent.

For ship procurement costs, three ship-system costs stood out. Most expensive is the power plant: propulsion and electrical generation and distribution. Second are the aviation systems: the catapults, aircraft and weapon elevators, and the arresting gear. Third are the radars. So to improve costs as well as performance, we planned to redesign those systems first.

But to do it all on one ship was considered too risky. So in 2000, the Navy and the DOD proposed, and Congress approved, an evolutionary plan with three ships starting with the last Nimitz -class carrier, CVN-77, and two new carriers, CVN-78 and -79. CVN-77 gets the most mature technology—radars from the Aegis program—first. Then CVN-78 gets the new power plant and catapults, and CVN-79 gets the new aircraft and weapon elevators.

In 2002, the DOD proposed a change to the plan due in part to the immaturity of the new radars. CVN-77 reverted back to a modified repeat of the Nimitz class with improvements, while the new radars were pushed to CVN-78. Also, CVN-78 was made the one-step transformation platform by pulling forward the new advanced arresting gear, with new aircraft and weapon elevators plus a completely new, redesigned interior.

In 2004 this plan was finalized and approved by Congress along with a decision to initially produce three new carriers: the Gerald R. Ford (CVN-78) by 2015, the John F. Kennedy (CVN-79) by 2020, and the Enterprise (CVN-80) by 2025.

Evolution Perpetuates the Legacy

Now we will have at least three new nuclear-powered aircraft carriers with 20 percent lower total-ownership costs, new phased-array radars, and a new nuclear-power plant and new electrical system capable of launching and recovering 80 of the newest aircraft in the Fleet with electromagnetic catapults and new electric arresting gears.

So what is on the horizon? Unmanned aircraft. Next year the Navy will land a stealthy autonomous aircraft, the X-47-B, on a West Coast carrier. Large as an A-6 but tailless, it has the potential to be a medium bomber as well as a surveillance aircraft. When unmanned aircraft are proven capable of landing and flying off a large carrier, we’ll be entering a whole new phase.

Remember the massive deck-loaded single launch that swarmed the Panama Canal and earned naval aviation its spurs in 1929? Well, imagine a deck full of Predator aircraft on the forthcoming Enterprise . With electromagnetic catapults, such small, lightweight unmanned vehicles can be launched by the scores by an electrically controlled catapult and brought back in with advanced arresting gear. Watch out: The swarm is coming back, just in time to be launched off a new generation of Enterprise —CVN-80.

1. E.B. Potter, The Naval Academy Illustrated History of the United States Navy (New York: Galahad Books, 1971), 147.

Captain Manvel served as an engineering duty officer specializing in aircraft carriers. He served on three, last as chief engineer on the USS America (CV-66) during Operation Desert Storm. He assisted in the supervision of construction of the USS Carl Vinson (CVN-70) and Theodore Roosevelt (CVN-71), led the development of the Incremental Maintenance Plan for the Nimitz class, and led the design of the new Ford class. He teaches naval architecture at the U.S. Naval Academy.